"Cannot resolve method getResources" when trying to execute getResources in non-activity method using method widely advocated here

Question

I have been trying to use getResources in a non-activity class. I found some advice on how to do so here. To use one of the suggested ways, by Lilzilala, (there are multiple, but mostly suggest the same thing), I have created a special class, used this to specify the resources as "res", and then instantiated this class using "new" in a line which invokes "getResources".

However, I'm getting a "cannot resolve method getResources" error on "getResources". I'm a bit of a noob, but don't know why this is happening. From what I can tell, this error happens when there simply isn't a resource with that name available. Which makes me think maybe Resources doesn't contain getResources() by default?

class executeTrimmer<Resdefine> {


    public class ResDefine {
        private Resources res;

        public ResDefine(Resources res)
        {
            this.res = res;
        }}


 Bitmap img1 = BitmapFactory.decodeResource(new ResDefine(getResources()),
        R.drawable.bmpname);
}

EDIT - following suggestions that I add context, I have tried this:

class executeTrimmer<Resdefine> {


private static Context context;
public executeTrimmer(Context context){
    this.context = context;
}

    public class ResDefine {
        private Resources res;

        public ResDefine(Resources res)
        {
            this.res = res;
        }}


 Bitmap img1 = BitmapFactory.decodeResource(new ResDefine(executeTrimmer.context.getResources),
        R.drawable.bmpname);

But this still brings up error "cannot resolve symbol getResources". I've tried multiple different ways to pass context to it, and consistently faced the same error.

Use context from constructor and then use getresources like context.getresources — Prajwal Waingankar, Oct 02 '20 at 16:21
@PrajwalWaingankar I thought the point of doing it this way was to avoid using context because it risks memory leaks? — Statsanalyst, Oct 02 '20 at 16:32
Also @PrajwalWaingankar, how exactly would I do that? Use context from constructor? — Statsanalyst, Oct 02 '20 at 16:37
When u r calling this class from an activity then pass that activities context as a constructor argument of this class. Create a constructor of this class above and then call that constructor in the activity from which u r calling this class and in that share the activity context. — Prajwal Waingankar, Oct 02 '20 at 19:22

PerracoLabs · Answer 1 · 2020-10-02T17:13:32.760

As you can see in the official documentation, "getResources" is Context's method, therefore you can't call it out from nowhere, neither statically. This method requires a context instance.

In your case you must at least pass a context to your class to be able to invoke it as next:

context.getResources()

I think you got confused from seen it being directly called inside Activities without a prefixed context, but as all Activities are actually a context, this is why there is no prefix.

To clarify. When called inside an activity, this:

getResources()

is the same as this:

this.getResources()

where the prefix "this." refers to the activity, which in turn is a context by itself.

On the other hand your code should be like next, without the ResDefine class. And notice that the decodeResource call is required to be inside a method and not at class level scope (this is not allowed in Java). And in fact you don't even need to use a context, so pass instead the Resources instance from the caller's class which is supposed to hold the context:

public class executeTrimmer {

    private final Resources res;
    
    public executeTrimmer(final Resources res) {
        this.res= res;
    }
    
    public void loadBitmap()
        Bitmap img1 = BitmapFactory.decodeResource(this.res, R.drawable.bmpname);
        ........
    }
}

And for the caller, next a very naive example, so may get an idea:

public class MainActivity extends Activity {

    @Override
    protected void onCreate(@Nullable final Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
  
        new executeTrimmer(this.getResources()).loadBitmap();
    }
}

This works and runs - thanks. But what does it actually do? How would I, say, use the output of this in a layout? — Statsanalyst, Oct 05 '20 at 22:11

"Cannot resolve method getResources" when trying to execute getResources in non-activity method using method widely advocated here

1 Answers1